hash-runner executes a command when a change is detected in specified files. It calculates the SHA256 hash of the files and compares them to the previous hash values stored in a file. If the hashes differ, the specified command is executed.

This tool is not an active file watcher that constantly checks for changes.

Use-case

It is designed to be used in conjunction with tools like turbo, where the watch mode may trigger unnecessary builds even when caching is used.

For example, consider the following turbo configuration:

{
  "$schema": "https://turbo.build/schema.json",
  "tasks": {
    "dev": {
      "dependsOn": ["@internal/some-package#build"],
      "cache": false,
      "persistent": true
    }
  }
}

When running turbo [watch] dev, it will trigger a build even when no changes are detected in @internal/some-package.

By using hash-runner, the build command will still run on @internal/some-package, but it won't actually execute the underlying build command unless changes are detected.

Installation

Node.js 20 or higher is required.

To install hash-runner, use npm:

npm install hash-runner --save-dev

Usage

hash-runner [--config <config-file>] [--force] [--silent]

CLI options:

• -c / --config <config-file>: Specify a custom configuration file.
• -f / --force: Force the creation of a new hash file and execute.
• -s / --silent: Suppress log output.

Configuration

hash-runner uses lilconfig to read configuration.

lilconfig will check the current directory for the following:

• a hash-runner property in package.json
• a .hash-runnerrc file in JSON or YAML format
• a .hash-runnerrc.json, .hash-runnerrc.js, .hash-runnerrc.ts, .hash-runnerrc.mjs, or .hash-runnerrc.cjs file
• a hash-runnerrc, hash-runnerrc.json, hash-runnerrc.js, hash-runnerrc.ts, hash-runnerrc.mjs, or hash-runnerrc.cjs file inside a .config subdirectory
• a hash-runner.config.js, hash-runner.config.ts, hash-runner.config.mjs, or hash-runner.config.cjs file

Configuration options

• include: An array of glob patterns specifying the files to include in the hash calculation.
• exclude: An array of glob patterns specifying the files to exclude from the hash calculation.
  • node_modules is always excluded and does not need to be specified.
• execOnChange: The command to execute when changes are detected.
  • hash-runner will exit with the status code of the executed command after completion.
• hashFile: The path to the file where hashes are stored.
  • It is recommended you add the hashFile to your .gitignore file.
• parallelizeComparisonsChunkSize: Will start parallelizing the hash comparison per specified number of file entries.
  • Default is 100 files, meaning that the hash comparison will be parallelized for every 100 files.

Examples

Run tsc when changes are detected in files in the src directory:

package.json:

{
  "scripts": {
    "build": "hash-runner",
    "build:files": "tsc"
  }
}

Example configuration file (.hash-runnerrc.json):

{
  "include": ["src/**/*.ts"],
  "exclude": ["dist/**"],
  "execOnChange": "npm run build:files",
  "hashFile": ".hashes.json"
}

hash-runner.config.js:

module.exports = {
  include: ['src/**/*.ts'],
  exclude: ['dist/**'],
  execOnChange: 'npm run build:files',
  hashFile: '.hashes.json'
};

npm run build will only run tsc when changes are detected in files in the src directory.

CI Mode

When running in a Continuous Integration (CI) environment, hash-runner will bypass hash checks and execute the specified command directly. This is controlled by the CI environment variable. To enable CI mode, set the CI environment variable to true:

{
  "scripts": {
    "build": "hash-runner",
    "build:ci": "CI=true hash-runner",
    "build:files": "tsc"
  }
}

This will bypass hash checks and execute the specified command directly.

API

In addition to the CLI, hash-runner can also be used programmatically:

import { HashRunner } from 'hash-runner';

const runner = new HashRunner('/path/to/config.json', { force: true });
await runner.run();

Constructor and Parameters

HashRunner(configPath?: string, options: HashRunnerOptions = {})

Parameters:

• configPath (optional): A string representing the path to the configuration file. If not specified, hash-runner will attempt to load the configuration from the current directory.
• options (optional): An object containing options to configure the behavior of hash-runner.

HashRunnerOptions

• force? (boolean): Force the creation of a new hash file and execute the command regardless of detected changes.
• silent? (boolean): Suppress log output when set to true.

Troubleshooting

This library uses debug to log messages. To enable debug messages, set the DEBUG environment variable to hash-runner.

DEBUG=hash-runner hash-runner